San Diego-based Waterfi is one of several companies developing waterproofing techniques to keep your electronics safe from water — whether it’s your bathtub, the pool or the ocean.

Waterfi President Royce Nicholas won’t say much about DualLayer, the material he uses, because he’s awaiting approval of his patent application. What he will say, though, is that he coats the interior of electronics with it, which allows air in, but not water. Unlike the material many of his competitors use, Nicholas says his can handle long-term direct exposure to water.

The Kindle Paperwhite is the latest addition to Waterfi’s family of electronics, after the iPod Shuffle, iPod Nano and Nike+ FuelBand.

Nicholas buys the devices, waterproofs them with DualLayer, and then sells them on the Internet and Amazon with complimentary headphones from San Diego-based X-1 Audio, which specializes in waterproof cases and headphones.

The company has doubled its sales each year since inception and is growing so fast that now Nicholas is expanding the operation.

Humble beginning

Waterfi started in 2010 with an inexpensive home experiment. Nicholas bought an iPod Shuffle. Then he took the device apart and coated its inner parts. He had it working within a day.

He sold his first waterproofed Shuffle, which retailed for $49, for $75 on eBay. Now he sells it for $140 on his own website and on Amazon.

Nicholas, 28, has an engineering degree from San Diego State University and worked with a manufacturing company in Poway before joining a biotech firm in Mira Mesa, where he learned about the problems water can pose for electronics.

The right idea

In 2010, he quit his job and started designing websites on a contract basis while searching for the right idea so he could start his own business. It took him nearly a year to strike the right one, but he knew it when he did.

“People on Amazon started rating (the waterproof Shuffle) five stars, and raving about it in their reviews,” he said. “It jumped up to the top of the list for waterproof MP3 players that people swim with.”

He kept raising his prices in an effort to manage the demand, but when the holiday season came, Nicholas had to hire some friends just to keep up with orders.

“We were just hanging out in my living room all day making these and watching TV,” he said. He kind of misses those days, he said.

Since then, sales have doubled each year to about $4 million in 2012, and Nicholas estimates that Waterfi now accounts for about one-quarter of Apple’s total iPod Shuffle sales. Apple does not report its sales numbers by model, but it sold nearly 5.6 million iPods sold during the second fiscal quarter of 2013, which ended in March. That number includes sales figures for the iPod Shuffle, Nano, Touch and Classic.